Well everything seems fine to me.
Your mobo is great, if you want to, you can SLI later. no problem.
Personally i do think that you dont need a x2 processor. If you only do gaming, then that CPU will do you great. It overclocks nicely as well.
The only problem is probably RAM. I think if you want to do serious gaming, you definitely needs 2gb or RAM. 1 Gb of normal RAM doesn't seem to match the 7900 GT extreme.
By the way, many people critisize the XFX brand of NVIDIA card. It sometimes causes overheat problems. If possible, choose a evga one.
DFI Lan party UT NF4 Ultra
AMD Opteron 146 2.0 Mhz @ 2.8 GHz
OCZ Gold Edition 2x512 MB DDR 500 timing 2.5-3-3-8 @ DDR 560
XFX GeForce 7600 GT 256 Mb GDDR3
Antec Lanboy Mini Tower Case
Antec True Control 550W ATX2.0 PSU
Maxtor 300 GB 7200 RMP SATA 16Mb Cache
17\'\' TFT Screen 12 ms